PAN基碳纤维制备过程中的组成演变

Evolution of composition in producing PAN based carbon fiber

通过对聚丙烯腈(PAN)原丝到碳纤维制备过程各阶段纤维质量和组成的变化的分析,研究了预氧化过程、低温碳化过程和高温碳化过程C、N、H和O的演变规律,结果表明:预氧化过程中伴随着O的结合,纤维中部分N、C和H发生脱除,N和H的脱除量随着O的增加量线性增加,其中1/4左右的H在此阶段脱除;低温碳化阶段是纤维大量脱除非碳成分的过程,N、H、O的脱除量占碳纤维制备过程总脱除量的50%左右,低温碳化也是C损失最大的一个阶段,占C总损失量的60%左右;高温碳化过程是纤维中N、H和O进一步脱除的过程,经过1250℃的高温碳化后,原来原丝中的N和H原子剩余量分别为13.7%和6.5%,O在此阶段几乎全部脱除,并且N和H的脱除量随高温碳化温度的提高而增加。通过对各阶段脱除原子数的相对含量的进一步分析,推测了预氧化过程PAN纤维的环化机理以及碳化阶段非碳成分的脱除形式。

The composition of fibers was analyzed at different stages in producing PAN based carbon fiber.The results showed that during stabilization of the PAN precursor,N and H contents decreased linearly with increasing of O,and more C atoms was reduced at higher stabilization temperature.At end of stabilization,about a quarter of H in the fibers was cast off.About 50% of non-carbon elements cast off during 700℃ pre-carbonization with about 60% total loss of C from PAN precursor to carbon fiber occurred in this stage.At stage of high temperature carbonization,the N、H and O were further driven off from the fibers with little C atoms lost.Only about 13.7% and 6.5% of N and H atoms resided in the fibers compared to N and H atoms in the precursors after treatment of 1250℃.The cast off mechanisms were predicted by comparing the relative amount of C,H,N and O atoms escaped from the fibers.